Ignition timer



Allg. 23, 1932. y C. H, DAVIS, JR 1,873,114

IGNITION TIMER Filed Nov. 26. 1930 A@SA I.

f3 l www l L?? @Mr Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE CHARLES IIAILL DAVIS, In., or ANDERSON, INDIANA.y A'ssIGNon ro DELoo-REMY conro1sr.A'rIoN,4 OE ANDERSON, INDIANA, A CORPORATION on DELAWARE IGNITION TIMER. y

Application mea November'zs, 1930. serial No. 498,342.

This invention relates to ignition apparatus for internal combustion engines, and more yparticularly to the engine v`speed responsive mechanism for controlling the rela- E tion between the ignition timer cam andengine part which vdrives it, whereby to vary the timing of the ignition impulse relative to the cycle of engine operation. y f

Speed responsive'ignition timing mechan'ism' generally comprises a plate carried by the ignition timer drive shaft,fand carrying movable weight members which moveaway from the shaft with increasing speed due to v increase in centrifugal force, and toward 152 the shaft with decreasing speed, due to the action of springs which yieldingly resist outward motion of the Weights. `The Weights cooperate with parts connected with the ignition timer cam which is mounted upon the 2 ignition timer drive shaft but which may rotate relative to the drive shaft. The ignition timer cam cooperates with the rubbing block of a circuit breaker lever to move the lever so that an ignition timer contact carried thereby will be separated from a stationary timer contact. In structures of this kind a spring is always employed to urge the circuit breaker lever into contact closing position when the cam does not touch the rubbing n $0 block and to maintain the rubbing block in contact with the cam ywhen engaged by the cam to separate the timer contacts.

' It is one of the objects of the present invention to improve speed responsive ignition timing` controlling mechanism in a manner such that the mechanism will be less affected by the retarding force which is intermittently applied to thetimer cam each time the cam engages the rubbing block vofthecircuit breaker lever, and'also so that the mechanism will be less affected by torsional vibrations transmitted from the 'engine shaft lto the ignition timer drive sha s In the disclosed` embodiment of the present invention this Objectis carried' out by increasing the mass directly rotating with the ignition timing cam without, however materially increasing the total weight of all ofthe rotatingr mass of the ignition timer. I

- have found that instead of mounting ythe weights and weight plate directly'upon the timer drive shaft, the desired results can be sec-uredby mounting the weight plate directly uponrthe ignition cam so that the polar inertia of the cam will be increased verysubstantially due to the fact that the cam now carries the weight plate and weights which had been formerly carried bythe timer drive shaft in the conventional ignition timer. The greater the mass rotating with the timer cam, the; less will be the retarding effect of the per1odic engagement of the rubbing block kwith the cam.

VFurther objects and advantages of the present invention will be apparent from ythe following description, reference being had to the accompanying drawing, wherein a preferred embodiment of one form of the present invention is clearly shown.

In ythe drawing: i

Fig. l is a vertical longitudinal sectionalk view of an ignition timery embodying the present invention. n Y

Fig. 2 is a fragmentary sectional view of parts shown in Fig. 1 drawn to a large scale in order to show details of construction, and is takenon'the line/242 of Fig. 3, along which also certain portions of the sectional view of Fig. l are taken.

Figs. 3 and 4 are sectional views taken respectively on the lines 3 3 and 4 4 of Fig. l.

20 designates an ignition distributor housing comprising a timer cup'21 and a shank 22 providing a bearing for an ignition timer drive shaft 23. The shaft 23 provides an extension 24 of smaller diameter providing a journal for a timer cam 25 mounted thereon and free to rotate relative thereto. The cam 25 isdri'vingly connected with, and supports an ignition distributor rotor 26 carrying a center Contact 27 and a distributing segment 28. lThe center contact 27 cooperates with a central, stationary distributor contact 29; and the segment cooperates with distributor posts 30 arranged in a circular row. The contact 29 and the posts 30 are electrically connected with metal sockets 3l and 32 reby which wires may be secured thereto.

The cam 25 cooperates with the rubbing block 33 of a. circuit breaker lever 34 pivoted upon a stud 35 carried by a circuit breaker plate 36 mounted in the cup 21. A leaf spring 37 urges the rubbing block 33 toward the cam 25 and serves to conduct the current to the circuit breaker lever 34 and a movable timer contact 38 carried thereby. lVhen the cam 25 is out of engagement with the rubbing block 33 the contact 38 is urged by the spring 37 into engagement with a stationary timer Contact 39.

As shown more clearly in Fig. 2, the hub 40 of the cam 25 is attached to a weight supporting plate 41 carrying studs 42 providing pivots for weights 43 which rest upon ywashers 44, and ridges 45 provided by the weight plate 41. Each weight 43 has an arm 46 cooperating with a surface 47 of a block 48 which is located upon the reduced upper portions 49 of studs 5() which are attached to a pla-te 51 attached to the shoulder 52 provided by the shaft 23. As shown more clearly in Fig. 2, the shoulder 52 provides a. bearing for the lower end of the hub 40 of cam 25. rlhe plate 48 provides a central hole through which the lower end of the hub 40 of the cam 25 extends. The upper end portion 49 of the studs 50 carry also a hold down plate 53 having olf set extensions 54 which project above the weights 43 and limit upward movement thereof with respect to the plate 41. Each pair of adjacent studs 42 and 50 are connected with the ends of a coiled spring G0, which tends to urge a surface 47 of the plate 48 toward a lever 46 of a weight 43 thereby urging the weight 43 toward the drive shaft extension 24. The hold down plate 53 is pressed on spring posts 50. Springs should not touch the hold down plate. As viewed in Fig. 3, the springs 60 tend to urge the block 48 in a counter-clockwise direction relative to the plate 41 or rather the plate 41 in a. clockwise direction relative to the plate 48. Motion of the plate 41 in this direction is resisted due to the fact that the larger portion of each stud 50 engages one side of a hole 61 in the plate 41 as more clearly shown in Fig. 4. The holes 6l are of such size as to permit relative rotation between the plate 41 and the plate 48 to permit advancing the cam 25 relative to the timer drive shaft 23.

As the speed of the shaft 23 increases, centrifugal force acting upon the weights 43 will overcome the resistance of the springs 60 causing tiese weights to rotate counterclockwise about their pivots 42 as viewed in Fig. 3, thereby causing the levers 46 to rock along the surfaces 47 of the plate 48, thus causing the plate 41 to be rotated in a counterclockwise direction relative to the plate 48 and hence relative to the shaft 23 which supports the plate 48. In this way the cam 25 which is directly attached to the weight plate 41 is caused to be rotated in a counterclockwise direction relative to the shaft 23 in order to advance the timing of the ignition with increasing engine speed. As the speed of the shaft 23 decreases, the springs 60 overcome centrifugal force acting upon the weights 43 to cause them to move toward the shaft extension 24 as viewed in Fig. 3 thereby causing the weight plate 41 to move in a clockwise direction relative to the drive shaft 23 whereby the ignition timing will be retarded as the speed decreases.

In the conventional ignition timer having speed responsive control of the relation between the timer drive shaftand the ignition timer cam, the weight plate and weights are mounted upon the timer drive shaft, the weight plate occupying the position of the plate 51 shown in Fig. 2. The plate corresponding to plate 48 shown in the drawing with which the lever arms of the weights cooperate, is mounted upon the hub of the timer cam in the conventional ignition timer. It is therefore apparent that in the present invention the mass rotating directly with the timer cam 25 has been materially increased by substituting for a plate attached t0 the hub of the timer cam and having about the weight of the plate 48 shown in the drawing, the combined mass of weight plate 41 and weights 43. This substitution of parts adds very materially to the polar inertia of the cam 25 in order that the automatic control of the ignition timing will be substantially less effected by torsional vibrations of the shaft 23 resulting from similar vibrations of the engine crank shaft, and will be substantially less affected by the retarding impulses to which the ignition cam 25 is intermittently subjected due to its intermittent contact with the circuit breaker lever rubbing block 33.

It will be apparent that these improvements in the construct-ion of the speed responsive mechanism have been provided without materially increasing the total weight of rotating parts of the timer Iand without appreciably increasing the cost of manufacture. As has been explained the disclosed embodiment of the present invention is designed to control an ignition timer cam which rotates counterclockwise, as viewed in the plan view. It will, therefore, be noted that the weights 43 are rocked in a trailing direction with respect to their pivoting posts 42, which rotate counterclockwise. It has been found that thisV arrangement tends to make the weights more stable because of air resistance than in the case of the conventional ignition timer using a centrifugal advance in which the weights are in leading positions with respect to their pivot posts.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is clalmed is as follows:

l. An ignition timer for internal combustion engines comprising, in combination, a circuit interrupter and a rotary cam for operatinO the same, and havin a tubular hub, a drlve shaft having an en portion on which the ycam hub is journalled, a weight plate attached to the hub, a lever plate attached to the drive shaft on the side of the weight plate remote from the cam, movable welghts 1ocated upon the side of the weight plate nearest the cam, arms on the side of the weight plate nearest the cam and cooperatingA with the weights, and means extending through the weight plate for rotatively connecting the arms and lever plate, and springs restralning movement of the weights due to centrifugal force.

2. An ignition timer for internal combustion engines comprising in combination;

a circuit interrupter and a rotary cam :forv

operating the same; a drive shaft in alignment with said cam; and speed res onslve means for connecting said cam an drive shaft for varying the angular relation between them, said means comprising a weight plate having spaced apertures concentric to the axis of said plate and carryin movable Weights, said plate attached to sald cam; a drive plate secured to said drive shaft and carrying studs extending through said apertures `o said Weight plate to support lever arms cooperating with said weights, said studs cooperating with said apertures permitting relative rotation between said weight plate and arms to advance the cam; and springs restraining movement of the weights due to centrifugal'force.

In testimony whereof I hereto ailix my signature.

CHARLES HALL DAVIS, JR. 

